JPH11300844A - Production of resin pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the practicality of a multilayered resin pipe for a pipeline of a cooling water system of an engine or the like. SOLUTION: A resin branch pipe 10 has a main pipe 12, a branch pipe 14 and end metal fittings 16,18. The main pipe 12 is a two-layered resin pipe wherein the innermost layer is coated with a coating layer and the innermost layer is formed by using a mixed resin of a PPS resin, nylon 6 and modified polyethylene and the coating layer is a resin layer formed by using nylon 6. The innermost layer and the coating layer are formed by co-extrusion and bonded through the fusion/integration of nylon 6 contained in both layers in common. At a time of the bending processing of the pipe, a bending place is heated to a temperature of 150 deg.C or higher and the m.p. of a polyamide or lower resin to be bent in this heated state. At a time of the pressure introduction of the end metal fittings, the pipe end parts are heated to about 120-205 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer resin pipe used in an air or cooling water circuit.

[0002]

2. Description of the Related Art Conventionally, this kind of resin pipe has been manufactured by injection molding of a single resin in consideration of productivity.
In this case, generally, polyamide resin such as nylon 66 mixed with glass fiber for reinforcement, or aromatic polysulfide resin (hereinafter abbreviated as PPS resin) which is polyphenylene sulfide or a modified product thereof is used. Had been.

[0003]

In such a resin pipe made of a single resin, characteristics resulting from the properties of the resin used, for example, heat resistance, weather resistance and toughness of a polyamide resin such as nylon 66 can be reduced. PPS resin is excellent in heat resistance, and antifreeze (LL
C) (LLC resistance).

As described above, since the performance of the resin pipe is determined by the resin used, attempts have been made to produce a multilayer resin pipe through coextrusion of different resins.
However, polyamide resin such as nylon 66 and PP
Since S resin does not have adhesiveness, peeling may occur due to propagation of vibration or the like even if it is simply multilayered through coextrusion. Then, when the layer is separated in this manner, water may enter into the separated portion, resulting in a decrease in strength and lacking practicality. Even if the resin layer made of PPS resin is multilayered so as to be an inner layer, since the inner layer is made of PPS resin, the toughness is low, so that bending processing is difficult, or a connecting pipe is pressed into a pipe end. In some cases, cracking may occur, and this point also lacks practicality.

The present invention has been made to solve the above problems, and has as its object to enhance the practicality of a multilayer resin pipe used in an air or cooling water system circuit.

[0006]

Means for Solving the Problems and Their Functions and Effects In order to solve the above problems, a method for manufacturing a resin pipe of the present invention is a method for manufacturing a multilayer resin pipe used for an air or cooling water system circuit. Is formed using a mixed resin obtained by mixing a polyamide resin with an aromatic polysulfide resin which is a polyphenylene sulfide or a modified product thereof, and an inner layer portion forming an inner layer of a pipe, and formed using the polyamide resin, A step of preparing a multilayer resin pipe having a coating layer covering the inner layer, wherein the inner layer and the coating are formed by co-extrusion of the mixed resin and the polyamide resin; and Heating the pipe at a temperature in the range from about 150 ° C. to the melting point of the polyamide resin, at least over the bending area, Characterized by a step of bending a.

In the present invention having the above structure, a multi-layer resin pipe in which the inner layer portion of the mixed resin is coated with a coating layer portion of a polyamide resin through co-extrusion of the resin, and at least the bending region is formed at the time of bending. The heating was performed at a temperature in the range of about 150 ° C. or higher and the melting point of the polyamide resin or lower. Then, in co-extrusion of the resin, the resin for forming the inner layer portion is a mixed resin obtained by blending a polyamide resin with a PPS resin (polyphenylene sulfide or an aromatic polysulfide resin which is a modified product thereof), In the bonding surface between the coating layer and the coating layer, the molten polyamide resin on the coating layer side and the molten polyamide resin on the inner layer side are fused, and the curing of the resin in this state causes the inner layer portion of the polyamide resin to the coating layer portion to harden. Develop adhesion. For this reason, the adhesive strength between the inner layer portion and the coating layer portion can be secured, and the peel resistance can be improved. Further, since the heating temperature at the time of bending is specified as described above, even if the PPS resin contained in the inner layer part lacks toughness as a property, both the inner layer part and the coating layer part have a low elastic modulus. To ensure bending workability. Further, even after cooling after the completion of the bending, the shape by the bending can be maintained. As a result, according to the present invention, it is possible to provide a multilayer resin pipe for air and cooling water systems having high practicality.

In this case, the heating temperature during bending is about 15
When the temperature is 0 ° C. or more, the inner layer portion and the coating layer portion can be kept in a stable low elastic modulus state, which is preferable. Further, it is preferable from the viewpoint of maintaining the shape after the bending as described above that the heating temperature during the bending is equal to or lower than the melting point of the polyamide resin in the coating layer portion. Examples of the polyamide resin include nylon 6, nylon 66, nylon 11, nylon 12, and the like.

[0009] The inner diameter of the pipe and the thickness of the inner layer portion and the coating layer portion are appropriately determined according to the circuit used. For example, it is determined according to the flow rate and pressure of the air flowing through the circuit and the cooling water, etc. For a cooling water circuit of an automobile, the inner diameter of the pipe is about 13 mm, and the thickness of the inner layer and the coating layer is about 1 mm each.
mm. In the case of a cooling water circuit for an automobile, the inner layer may have a thickness of about 0.3 mm or more.

By determining the thickness of the inner layer and the like in this manner, it is possible to secure the mechanical strength of a circuit for a cooling water system of an automobile, and to make the polyamide resin and P
The properties (toughness resistance, workability) of the PS resin itself can be exhibited. More specifically, the inner layer portion is set to 0.3
By setting the thickness to at least mm, sufficient LLC resistance was ensured by the PPS resin even when this inner layer portion was the innermost layer of the pipe. In addition, when the coating layer portion is the outermost layer, the polyamide resin exhibits weather resistance and can prevent, for example, salt damage.

The mixing ratio of the PPS resin and the polyamide resin in the mixed resin for forming the inner layer portion is PPS
It is preferable that the resin has a rich compounding ratio with respect to the polyamide resin. For example, the compounding ratio between the PPS resin and the polyamide resin may be about 2-3: 1. This is preferable because the compound-rich PPS resin can reliably exhibit LLC resistance in the inner layer. Further, by dispersing the polyamide resin in the compound-rich PPS resin and mixing the polyamide resin in the inner layer portion, it is possible to ensure the adhesiveness between the polyamide resin and the coating layer portion.

The method for manufacturing a resin pipe according to the present invention having the above-described structure can also adopt the following modes. In the first mode, in the manufacturing method according to the present invention, the step of preparing the resin pipe is performed by using polyphenylene. An aromatic polysulfide resin, which is a sulfide or a modified product thereof, is formed as a third resin, and has an innermost layer portion inside the inner layer portion in addition to the inner layer portion and the coating layer portion, A step of preparing a multilayer resin pipe in which the inner layer, the covering layer, and the innermost layer are formed by co-extrusion of the mixed resin, the polyamide resin, and the third resin.

According to the first aspect, the adhesiveness of the inner layer portion to the coating layer portion of the polyamide resin is developed at the joint surface between the inner layer portion and the coating layer portion as described above, and the inner layer portion and the innermost layer portion are formed. In the bonding surface with the PPS resin, the PPS resin contained in both of the layers is fused to exhibit adhesiveness. For this reason, the adhesive strength of each layer portion of the resin pipe in which the innermost layer portion, the inner layer portion, and the coating layer portion are laminated in this order can be secured, and the peeling resistance can be improved. Therefore, according to the first embodiment, it is possible to provide a multilayer resin pipe for air and cooling water systems having high practicality. The innermost layer is made of PPS resin. However, since the innermost layer has a low modulus of elasticity due to heating during the above-mentioned bending, there is no problem in bending.

According to a second aspect, in the manufacturing method of the present invention or the first aspect, the outer diameter of the resin pipe is about 10 to 40% larger than the inner diameter thereof, and the resin pipe is press-fitted into an end of the resin pipe. Preparing the end press-fitting member, and heating the end of the resin pipe at a temperature in the range of not less than about 120 ° C. and not more than about 10 ° C. lower than the melting point of the polyamide resin. The method may include a step of press-fitting the end portion.

In the second aspect, when the end press-fitting member is press-fitted, the heating temperature of the end of the resin pipe is specified as described above, so that the PPS resin in the inner layer portion or the innermost layer portion has toughness as a property. Even if it is lacking, the inner layer, the innermost layer, and the coating layer are all in a state of low elasticity to secure the expandability of the pipe and facilitate the press-fitting of the end press-fitting member. Furthermore, after cooling after the end of the press-fitting of the end press-fitting member,
The elasticity is almost restored to the original state before heating, and the sealing property is exhibited. Therefore, according to the second aspect, the multilayer resin pipe for the air or cooling water system can be connected to another member or pipe via the end press-fitting member, and the sealing property can be secured at the time of the connection. For this reason, versatility in the circuit configuration of the air or cooling water system can be improved.

In this case, if the outer diameter of the end press-fitting member is larger than the inner diameter of the resin pipe by about 10% or more, that is, if the expansion ratio when the end press-fitting member is press-fitted into the resin pipe is about 10% or more. It is preferable to obtain a sealing property of about 1 MPa or more required for pipe connection. In particular,
When the expansion rate was about 23%, a sealing property of about 3 MPa could be obtained. If the expansion ratio is about 40% or less, the workability at the time of press-fitting is not remarkably reduced, the point at which the pipe expansion occurs relatively uniformly, and the frequency of occurrence of cracks in the pipe at the time of press-fitting. Is preferred from the viewpoint of low. Further, when the heating temperature at the time of press-fitting the end-portion press-fitting member is about 120 ° C. or more, the inner layer portion and the coating layer portion have a low elastic modulus, so that the pipe expandability is preferably secured. If the heating temperature at this time is not more than about 10 ° C. lower than the melting point of the polyamide resin in the coating layer, it is preferable from the viewpoint of restoring the elastic modulus after press-fitting the end press-fitting member as described above.

According to a third aspect, in the production method of the present invention or the first aspect, a step of preparing a branch pipe formed of the polyamide resin is performed, and a step of forming a through hole formed in the resin pipe is performed. And fixing the branch pipe to the coating layer by heat fusion.

According to a fourth aspect, in the manufacturing method of the present invention or the first aspect described above, a pipe formed of the mixed resin or the third resin and fitted in a through hole formed in the resin pipe. A step of preparing a branch pipe having a body part, a step of fitting the pipe part into a through hole of the resin pipe, and fixing the branch pipe through heat fusion between the pipe part and the through hole; Can be provided.

According to these embodiments, the circuit can be easily branched by the highly practical resin pipe. Further, since the branch pipe that causes the branch of the circuit is fixed by heat fusion between the polyamide resin in the branch pipe and the coating layer, or heat fusion between the branch pipe body and the through hole of the resin pipe, It is rich in water tightness and is preferable.

[0020]

Other Aspects of the Invention The present invention can also adopt the following other aspects. The first other aspect is that the inner layer portion is made of polyphenylene sulfide or an aromatic polysulfide which is a modified product thereof. A softening material such as an ethylene / glycidyl methacrylate or an ethylene / propylene copolymer ("Tuffmer" manufactured by Mitsui Petrochemical Co., Ltd.) for improving the low-temperature impact property and the extrusion moldability of the polyamide resin and the PPS resin to the fide resin. P0680 (trade name)).

In the first other embodiment, the softening material blended in addition to the polyamide resin can enhance the low-temperature impact resistance of the inner layer portion and improve the extrusion moldability.
preferable. In this case, the mixing ratio of the softening material is P
It is preferable that the PS resin is also rich in the softening material. For example, the blending ratio between the PPS resin and the softening material may be about 2-3: 1. This is preferable because the compound-rich PPS resin does not impair LLC resistance in the inner layer. In addition, compounding rich PP
By dispersing the softening material in the S resin and mixing it in the inner layer portion, it is possible to obtain low-temperature impact resistance and extrusion moldability of the inner layer portion.

[0022]

Next, embodiments of a resin pipe according to the present invention will be described based on examples. 1 is a schematic perspective view of a resin branch pipe 10 according to an embodiment, FIGS. 2 and 3 are cross-sectional views taken along lines 2-2 and 3-3 in FIG. 1, FIG. 4 is an enlarged view of a main part of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. The resin branch pipe 10 of this embodiment is used for a cooling water system in an automobile engine, that is, a circulation line of antifreeze (LLC) containing ethylene glycol as a main component, and has the following configuration.

As shown in FIG. 1, a resin branch pipe 10
Is a three-dimensionally bent main pipe 12 and a branch pipe 1 for branching fluid from the pipe.
4 and end fittings 16 and 18 at both ends of the pipe. The main pipe 12 has a pipe inner diameter of about 13 mm. As shown in FIG. 2, the innermost layer 22 (about 1 mm in thickness) is covered with a coating layer 24 (about 1 mm in thickness) over the pipe line.
Layer of resin pipe. The innermost layer 22 is made of PPS resin,
This is a resin layer formed using a mixed resin obtained by mixing nylon 6, which is one of polyamide resins, and the above-mentioned softening material for improving low-temperature impact resistance and extrusion moldability. In the innermost layer 22, the mixing ratio of the PPS resin to the polyamide resin and the softening material is rich,
More specifically, 25 watts to 50 wt% rich PPS resin
t% nylon 6, 5 wt% ethylene / glycidyl methacrylate, and 15 wt% ethylene / propylene copolymer are blended, and nylon 6 and the above softener are dispersed and mixed in this blend-rich PPS resin. It is in such a state. The coating layer 24 is a resin layer formed using nylon 6, which is one of polyamide resins.
The innermost layer 22 and the coating layer 24 are formed simultaneously by co-extrusion described later. In addition, in the coating layer 24,
Nylon 11 or nylon 12 may be used instead of nylon 6.

As shown in FIG. 3, the branch pipe 14 includes a tubular pipe part 26 forming a branch pipe, a flange part 28 formed at the base thereof and in close contact with the outer periphery of the main pipe 12, and a pipe part. 26 and a fitting portion 30 at the end. In this case, the branch pipe 14 is an integrally molded product obtained by injection molding of a polyamide resin (nylon 6) in which glass fibers are mixed at a ratio of about 30 wt% for reinforcement. As shown in FIGS. 3 and 4, the branch pipe 14 has a state in which the fitting portion 30 is fitted into a branch hole 32 formed in the main pipe 12.
In a bonding region A extending from the back surface of the flange portion 28 to the outer peripheral surface of the fitting portion 30, the bonding portion 30 is bonded and fixed to the main pipe 12.
The state of this bonding will be described later.

As shown in FIG. 5, the end fitting 16 is a fixing fitting for fixing the resin branch pipe 10 to a member such as an engine or a radiator (not shown), and includes a flange 34 having a through hole for a fixing screw. And a fitting pipe portion 36 fitted to the main pipe 12. The fitting tube 36 is
When pressed into the end of the main pipe 12, the pipe
The diameter is larger than the inner diameter of the pipe so that the pipe expands by about 3%.
The outer periphery has a so-called bamboo shoot-shaped stopper. And
The end fitting 16 is pressed into the end of the main pipe 12 at a predetermined temperature and fixed to the main pipe 12. In this case, the end fitting 16 expands the main pipe 12 at an expansion rate of about 23%, and the elasticity of the main pipe 12 is almost restored to the state before heating by cooling after the fitting is pressed. Since the metal fitting 16 has a bamboo-shaped stopper, it is fixed while maintaining high strength. When the detachment strength of the end fitting 16 thus fixed was measured, the detachment strength at room temperature was about 20.4 N (about 200 kgf) or more. After the end fitting 16 was press-fitted, the sealability of the press-fitted portion was evaluated.
High sealing performance was obtained. The end fitting 18 is a connecting fitting for fitting and connecting the resin branch pipe 10 to another pipe or the like, and is fitted and fixed to the main pipe 12 similarly to the end fitting 16 described above.

Next, a method of manufacturing the resin branch pipe 10 will be described. FIG. 6 is an end view schematically showing a main part of a multilayer extrusion molding machine for co-extrusion of different resins. As shown in the figure, the multilayer extrusion molding machine has a die head 40
The first head 42 for extruding the coating layer 24 and the coating layer 2
4 and a second head 44 for layering the innermost layer 22
And a third head 46 for extruding the innermost layer 22. The first head 42 is for extruding the coating layer 24 with its outer diameter defined. Third head 46
Is for extruding the innermost layer 22 with its inner diameter defined, and has a mandrel portion 47 surrounded by the first head 42. Then, the first head 42 and the second head 4
4, a resin (nylon 6) for forming the coating layer 24 is extruded in a molten state, and almost simultaneously with the extrusion, the innermost layer 2 is formed between the second head and the third head 46.
2 (a mixed resin of PPS resin, nylon 6, and modified polyethylene) is extruded in a molten state. The resin co-extruded in this manner becomes the coating layer 24 and the innermost layer 22 when passing between the first head 42 and the mandrel portion 47 of the third head 46, respectively. Covered with the coating layer 24
The layers of pipe are extruded straight. The pipe thus extruded passes through a sizing die (not shown) downstream of the die head portion 40, and during the passage of the die,
A pipe having the above inner diameter (about 13 mm) and each layer thickness (about 1 mm) is cooled and then
It becomes 2. The extrusion amount of the resin for forming the coating layer (nylon 6) and the resin for forming the innermost layer (mixed resin) are adjusted so as to obtain the thickness of each of the above-mentioned layers.

In the main pipe 12 obtained as described above, the resin for forming the coating layer 24 and the innermost layer 22 is cured, so that the coating layer 24 and the innermost layer 22 are mutually separated as described below. Glue. FIG. 7 is a schematic diagram schematically showing a state of adhesion between the coating layer 24 and the innermost layer 22. As shown in FIG. 7, in the innermost layer 22, when the resin is in a molten state, nylon 6 is added to the molten PPS resin.
And the above-mentioned softening material are in a molten and mixed state, and some nylon 6 is present at the interface in the innermost layer 22.
On the other hand, in the coating layer 24, the nylon 6 is still in a molten state. For this reason, at the joining surface (interface) between the innermost layer 22 and the coating layer 24, the molten nylon 6 on the coating layer 24 side and the molten nylon 6 on the innermost layer 22 side fuse, and in this state, the resin hardens. Get up and unite. Therefore, at the joining surface between the innermost layer 22 and the covering layer 24, the nylon 6
As a result, a so-called anchor effect as schematically shown in FIG. 7 occurs, whereby the innermost layer 22 and the coating layer 24 are firmly adhered and fixed. Accordingly, the main pipe 12 in which the innermost layer 22 and the coating layer 24 are firmly adhered and fixed is obtained from the multilayer extrusion molding machine. When nylon 11 or nylon 12 is used instead of nylon 6 as described above, the molten nylon 6 on the side of the coating layer 24 and the innermost layer 22
Is fused with the melted nylon 11 or nylon 12, and the innermost layer 22 and the coating layer 24 are firmly adhered and fixed by the anchor effect.

The straight main pipe 12 thus obtained is subjected to bending. That is, a bendable rubber mandrel (not shown) is inserted into the main pipe 12 and arranged at the bent portion shown in FIG. Next, the main pipe 12 in this state is immersed in silicon oil maintained at a temperature of about 150 to about 215 ° C. for about 3 to 5 minutes, and then set in a three-dimensional bending die (not shown). And
The three-dimensional bending process is performed by cooling to room temperature while being set in the three-dimensional bending die. Thereby, the curved main pipe 12 shown in FIG. 1 is obtained. After the bending, a through-hole 32 is punched out at a place where the branch pipe 14 is installed.

As described above, the main pipe 1 is bent at the time of bending.
2 is heated to a temperature of about 150 ° C. to about 215 ° C., whereby the innermost layer 22 and the coating layer 24 are both in a state of low elasticity to ensure bending workability, and after cooling after completion of bending. Therefore, the shape by bending can be maintained.
In this case, the upper limit of the heating temperature was set to the melting point of nylon 6 contained in the coating layer 24 (about 215 ° C.). Therefore,
When nylon 11 or nylon 12 is used instead of nylon 6, the melting point of nylon 11 or nylon 12 may be set to the above-mentioned upper limit of temperature.

Next, a preformed branch pipe 14 is prepared, and the back surface of the flange portion 28, the outer peripheral surface of the fitting portion 30 and the through hole 32 of the main pipe 12 in the branch pipe 14 are prepared.
Is heated to about 250 degrees, and the resin on the back surface of the flange portion 28, the outer peripheral surface of the fitting portion 30 and the periphery of the through hole 32, that is, the nylon 6, is melted. Then, in this state, the fitting portion 30 of the branch pipe 14 is fitted into the through hole 32, and the branch pipe 14 is pressed against the main pipe 12 so that the flange 28 closely adheres to the surface of the main pipe 12,
Continue pressing until the resin hardens. This allows
The branch pipe 14 is heat-fused to the main pipe 12 and is liquid-tightly adhered and fixed over an adhesive area A (see FIG. 4) from the back surface of the flange 28 to the outer peripheral surface of the fitting portion 30.

Subsequently, end fittings 16 and 18 are pressed into both ends of the main pipe 12. That is, first, the end of the main pipe 12 is immersed in silicon oil maintained at a temperature of about 120 to about 205 ° C. for about 3 to 5 minutes. afterwards,
The end fittings 16 and 18 are press-fitted to complete the resin branch pipe 10. The press fitting of the end fittings 16 and 18 may be performed before bending.

As described above, by expanding the main pipe 12 to a temperature of about 120 to about 205 ° C. at the time of press-fitting the end fittings, the pipe expandability (expansion rate of about 23% in this embodiment).
To ensure easy press-fitting of the end fittings 16 and 18, and after cooling after the press-fitting of these fittings, the elasticity is substantially restored to the original state before heating, thereby exhibiting sealing properties. be able to. In this case, the upper limit of the heating temperature is the melting point of nylon 6 contained in the coating layer 24 (about 215).
℃) about 10 ℃ lower. Therefore, nylon 6
In the case where nylon 11 or nylon 12 is used in place of the above, a temperature lower by about 10 ° C. than the melting point of nylon 11 or nylon 12 may be set as the above temperature upper limit.

The resin branch pipe 1 of the present embodiment described above
When 0 was attached to the engine and a durability test was performed, the following results were obtained. Resin branch pipe 1 of this embodiment
At 0, almost no decrease in the material strength and elongation was observed, and the same level of LLC resistance as that of the pipe made of PPS alone was obtained. This is largely attributable to the fact that the innermost layer 22 is set to about 1 mm. When the innermost layer 22 is set to 0.2 mm, there is a possibility that LLC may be transmitted and the coating layer may be eroded. Therefore, it is preferable from the viewpoint of LLC resistance that the innermost layer 22 be 0.3 mm or more, and it is more preferable that the innermost layer 22 be about 1 mm as in the present embodiment.

Further, as described above, since the temperature is controlled at the time of bending or press fitting of the end fitting, the bending can be performed without any trouble, and the end fitting can be fixed with high sealing property. Therefore, it is possible to provide a multilayer resin pipe for the cooling water system having high practicality, and it is possible to enhance the versatility in the circuit configuration of the cooling water system.

No crack or buckling was observed at the end of the pipe when the end fittings 16 and 18 were press-fitted. This is mainly due to the temperature control described above, but it can also be said that the innermost layer 22 and the coating layer 24 were formed as follows. That is, as described above, the resin branch pipe 1 in which the ratio of the thickness of the innermost layer 22 to the thickness of the coating layer 24 is 1: 1, the thickness of the innermost layer 22 is about 1 mm, and the coating layer 24 is added to the innermost layer 22.
The mechanical strength was ensured by setting the thickness of 0 itself to about 2 mm. When the innermost layer 22 is, for example, 0.2 mm, cracking or buckling may occur. Therefore, if the thickness of the innermost layer 22 and the coating layer 24 is set to the above relationship in addition to the temperature control described above, it can be said that the inner layer 22 and the coating layer 24 are more preferable from the viewpoint of avoiding cracking and buckling at the time of press-fitting the end fitting.

After the continuous use test for about 168 hours, the resin branch pipe 10 was divided along the axis to examine whether or not the resin layer was peeled off. As a result, no resin layer was peeled off. This is because the innermost layer 22 is made of a mixed resin in which NPS 6 is mixed with PPS resin and the coating layer 24 is made of nylon 6, so that the bonding surface (interface) between the innermost layer 22 and the coating layer 24 is formed.
In the above, the molten nylon 6 of both layers is fused, and the resin is cured in this state to produce an anchor effect, whereby the innermost layer 22 and the coating layer 24 are firmly bonded and fixed. Therefore, durability and reliability when the resin branch pipe 10 is a resin pipe for cooling the engine can be improved. In addition, instead of this nylon 6, nylon 1
The same was true when using No. 1 or Nylon 12.

Further, since the coating layer 24 made of nylon 6 which is the outermost layer in the main pipe 12 has a thickness of about 1 mm, the coating layer 24 can prevent salt damage to the same extent as a nylon 6 single pipe. It is preferable. Moreover, in the present embodiment, the mixed resin for forming the innermost layer 22 is
Since the nylon 6 and the above softening material were blended in the PPS resin, the innermost layer 22 was formed by the softening material.
This is preferable because the flexibility at the time of bending the conduit can be increased by improving the low-temperature impact resistance of the resin or by improving the extrudability.

As a result, according to this embodiment, the resin branch pipe 10 can be provided as a practically useful resin pipe for cooling an engine.

The resin branch pipe 10 is made of nylon 6
Since the branch pipe 14 is formed by heat-sealing nylon 6 to the main pipe 12, the watertightness at the branch point can be ensured, and the cooling water can be branched without fail.

The embodiments of the present invention have been described above.
The present invention is not limited to the above-described examples and embodiments at all, and it goes without saying that the present invention can be implemented in various modes without departing from the gist of the present invention.

For example, in the above embodiment, the two-layer resin branch pipe 10 having the innermost layer 22 and the covering layer 24 is used. However, as shown in FIG. 8, a three-layer resin branch pipe 10A may be used. . This resin branch pipe 10A is
An innermost layer 21 formed of a PPS resin, and an intermediate layer 2 formed of a mixed resin obtained by mixing nylon 6 with the PPS resin.
2A and a coating layer 24 made of nylon 6. In this resin branch pipe 10A, the intermediate layer 22
A corresponds to the innermost layer 22 in the above embodiment, and the innermost layer 21 and the intermediate layer 22A are connected to the intermediate layer 22A and the coating layer 24 through the fusion / integration of the PPS resin common to each layer. Through the fusion and integration of the nylon 6, the adhesives are firmly fixed. And even with this resin branch pipe 10A, high practicality can be exhibited like the resin branch pipe 10. In order to enhance the effectiveness of preventing salt damage, the coating layer 24
The outermost coating layer for coating this is polymethylpentene (4
-Polypentene-based polyolefin) to form a four-layer resin pipe.

Also, instead of nylon 6, nylon 6
6, nylon 11, nylon 12, and the like can be used. When nylon 66 is used, heat resistance and prevention of salt damage can be more effectively achieved.

Further, since a high sealing property can be obtained at the time of press-fitting the end fitting as described above, the following deformation can be made. In this modification, a so-called three-way branch pipe 14A shown in FIG. 9 is used instead of the branch pipe 14 shown in FIG. Then, the main pipe 12 is press-fitted and fixed to the bamboo-shaped ends at both ends of the branch pipe as described above. According to this modification, a pipe branched at an appropriate location can be easily manufactured.

Further, the branch pipe 14 shown in FIG. 3 has a flat plate-like flange 28, and the portion of the main pipe 12 where the branch hole 32 is formed is deformed flat. This is preferable because the branch pipe 14 can be easily fitted into the branch hole 32.

Further, the branch pipe 14 is formed from a mixed resin obtained by blending nylon 6 with a PPS resin,
It can also be deformed to be formed from PPS resin.
As described above, according to the modified example of the branch pipe 14 formed of the mixed resin, the nylon included in the branch pipe 14, the coating layer 24, and the innermost layer 22 is formed on the back surface of the flange portion 28 and the upper outer peripheral surface of the fitting portion 30. 6 by heat fusion occurs, and the fitting portion 3
On the outer peripheral surface of the lower part 0, adhesion occurs due to thermal fusion of the PPS resin contained in the branch pipe 14 and the innermost layer 22. Also,
According to the modified example of the branch pipe 14 formed of the PPS resin, the bonding of the PPS resin contained in the branch pipe 14 and the innermost layer 22 occurs by heat fusion on the lower outer peripheral surface of the fitting portion 30. Therefore, even in these modified examples, the branch pipe 14
To the main pipe 12 in a liquid-tight manner.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a resin branch pipe 10 according to an embodiment.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is a sectional view taken along line 5-5 in FIG. 1;

FIG. 6 is an end view schematically showing a main part of a multilayer extrusion molding machine for co-extrusion of a resin.

FIG. 7 is a schematic diagram schematically showing a state of adhesion between the coating layer 24 and the innermost layer 22.

FIG. 8 is a sectional view of a three-layer resin branch pipe 10A.

FIG. 9 is a cross-sectional view of a main part of a modified example of the resin branch pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Resin branch pipe 10A ... Resin branch pipe 12 ... Main pipe 14 ... Branch pipe 16,18 ... End fitting 21 ... Innermost layer 22 ... Innermost layer 22A ... Intermediate layer 24 ... Coating layer 26 ... Pipe section 28 ... Flange Reference Signs List 30 fitting part 32 through hole 32 branch hole 34 flange 36 fitting pipe part 40 die head part 42 first head 44 second head 46 third head 47 mandrel part A bonding area

Claims (5)

[Claims] 1. A method for producing a multilayer resin pipe used in an air or cooling water circuit, comprising using a mixed resin obtained by blending a polyamide resin with polyphenylene sulfide or an aromatic polysulfide resin which is a modified product thereof. An inner layer portion forming an inner layer of a pipe, and a coating layer portion formed using the polyamide resin and covering the inner layer portion, wherein the inner layer portion and the coating layer portion are formed of the mixed resin. Preparing a multi-layer resin pipe formed by co-extrusion of the polyamide resin; and preparing the prepared resin pipe at a temperature in the range of about 150 ° C. or higher and the melting point of the polyamide resin or lower over at least the bending region. Heating the resin pipe and bending the heated resin pipe. 2. The method for producing a resin pipe according to claim 1, wherein the step of preparing the resin pipe uses polyphenylene sulfide or an aromatic polysulfide resin which is a modified product thereof as the third resin. The inner layer, the inner layer and the covering layer in addition to the inner layer, the inner layer, the covering layer, and the inner layer are the mixed resin and the polyamide resin. And a step of preparing a multilayer resin pipe formed by co-extrusion of the third resin. 3. The method for manufacturing a resin pipe according to claim 1, wherein the resin pipe has an outer diameter that is about 10 to 40% larger than an inner diameter of the resin pipe, and is press-fitted into an end of the resin pipe. Preparing an end press-fitting member, and heating the end of the resin pipe at a temperature in the range of about 120 ° C. or more and about 10 ° C. or less lower than the melting point of the polyamide resin, A method for manufacturing a resin pipe, comprising a step of press-fitting the end portion. 4. The method for producing a resin pipe according to claim 1, wherein a step of preparing a branch pipe formed of the polyamide resin, and a place where a through hole formed in the resin pipe is formed. And heat fixing the branch pipe to the coating layer to fix the branch pipe. 5. The method for manufacturing a resin pipe according to claim 1, wherein the pipe is formed of the mixed resin or the third resin, and is fitted into a through hole formed in the resin pipe. A step of preparing a branch pipe having a body part; a step of fitting the pipe part into a through hole of the resin pipe; and fixing the branch pipe through heat fusion between the pipe part and the through hole. A method for manufacturing a resin pipe, comprising: